A more reliable DSC-based methodology to study crystallization kinetics: Application to poly(ether ketone ketone) (PEKK) copolymers. (24th October 2018) - Choupin, Tanguy
Abstract: To quantify the isothermal crystallization kinetics of poly(ether ketone ketone) (PEKK), the integration of the crystallization peak measured using differential scanning calorimetry is rendered difficult due to the thermal transient effects at the start of enthalpy recording. The different attempts to extrapolate this peak beginning often lead to false values of the Avrami exponent. A new crystallization kinetic assessment method is established here based on the derivative of the Hillier crystallization kinetic model. This method consists of directly fitting the transformation rate to the heat flow of the experimental crystallization, thus avoiding the extrapolation of the crystallization peak beginning. This method is successfully applied to two different PEKK grades with different crystallization kinetics. The identified crystallization parameters are modelled as a function of the crystallization temperature, and based on these modeling results, time-temperature-transformation diagrams of crystallinity were built to provide a useful tool for PEKK processing. Graphical abstract: Highlights: Method is based on derivative expression for crystallization Hillier model. Model fitting directly on the crystallization heat flux measured by DSC. The method avoids the extrapolation of the crystallization peak beginning. PEKK Crystallization kinetic modeling including primary and secondary crystallization.